1. Field of the Invention
This invention relates to electrical interconnection devices, and more particularly to a removable pin carrier for positioning male electrical contacts on a printed circuit board.
2. Description of Related Art
Numerous means are known today for interconnecting electrical and electronic components. One common means for interconnecting electronic components involves installing male contact pins made of an electrically conductive material on a substrate, such as a printed circuit board (PCB), upon which the electronic components are mounted. At least one of the male contact pins is electrically coupled to one or more of the electronic components of the PCB. Similarly, female contact receptacles and electronic components are mounted on a substrate, such as a second PCB. At least one of the female contacts is electrically coupled to one or more of the electronic components of the second PCB. The male contact pins of the first PCB are aligned with the female contact receptacles of the second PCB, and each male contact pin mates with a corresponding one of the female contact receptacles. Thus, those components of the first PCB which are coupled to male contact pins can be electrically coupled to those components of the second PCB which are coupled to female contact receptacles.
Typically, a plurality of male contact pins are bound together by an insulating housing which aligns the pins with respect to one another and to the printed circuit board on which they are to be soldered. Likewise, the female contact receptacles are typically bound together within a housing. The housing provides very good registration between the male contact pins and mounting holes of a PCB, and between the male contact pins and corresponding female contact receptacles. However, the housing takes up valuable space, or "real estate", on PCBs and projects above the surface of a PCB. Therefore, many attempts have been made to devise a removable pin carrier that would allow the male contact pins to be registered to the PCB and the female contact receptacles, but which could be removed later, leaving only the male contact pins connected to the PCB.
FIGS. 1a-1d illustrate one example of a prior art system in which a pin carrier 2 holds male contact pins 1 in registration prior to installation, and which is removed after the male contact pins 1 have been soldered to a PCB 3. See IBM Technical Disclosure Bulletin, Bunnell, K. J., Singh, P., Thakkar, A. J., and Tomassini, E. V. (Vol. 26, No. 6, November 1983). Two embodiments of the removable pin carrier are described in this reference. In the first, illustrated in FIG. 1a-1c, the pins 1 are installed into a pin carrier 2 such that only the portion of the pin 1 that enters a PCB 3 and a very small portion of the pin 1 that remains above the PCB 3 are exposed. The male pins 1 are supported in a PCB 3 by the pin carrier 2 with sufficient friction to retain the pins 1 in the pin carrier during processing. The pins 1 extend below the carrier 2 a distance necessary to be fixed to the PCB 3 and extend above the PCB 3 a distance necessary to allow the pins 1 to mate with corresponding female contact receptacles. The pins 1 are soldered onto the PCB 3. Upon completion of the soldering operation, the pin carrier 2 is removed, leaving only the male pins 1 connected to the printed circuit board 3. In the second embodiment, illustrated in FIG. 1d, the pins 1 are installed in the pin carrier 4 such that the pins 1 protrude through the pin carrier 4 a significant amount.
The first embodiment can register the male contact pins 1 to a very high accuracy, thereby ensuring very close tolerance in locating the pins 1. However, the large thermal mass of the pin carrier 2 makes heating the male contact pins 1 during a soldering operation more difficult (i.e., heating the male contact pins 1 requires more thermal energy). As the number of male contact pins 1 being installed increases, it is more desirable to use less thermal energy to heat each male contact pin 1.
The second embodiment has a much lower thermal mass. However, greater protrusion of the male contact pins 1 from the pin carrier 4 makes registration of the male contact pins 1 less precise. Precision registration is critical when very large numbers of male and female contacts are to be mated to one another at once, and particularly when the dimensions of the contacts are very small, as is the case in many of today's applications.
Therefore, there is a need for a removable pin carrier that permits male contact pins to be located upon a PCB with a very high accuracy with respect to the PCB and the position of each other male contact pin. There is also a need for a removable pin carrier which has a very low thermal mass, thereby allowing the male contact pins to be heated to the temperature required to flow solder with a minimal expenditure of thermal energy.
The present invention is a pin carrier that provides very accurate registration of the male contact pins, while minimizing the thermal mass in contact with each male contact pin.